Low-cost, single-mode diode-pumped Cr:Colquiriite lasers

Abstract

We present three Cr3+:Colquiriite lasers as low-cost alternatives to Ti:Sapphire laser technology. Single-mode laser diodes, which cost only $150 each, were used as pump sources. In cw operation, with approximately 520 mW of absorbed pump power, up to 257, 269 and 266 mW of output power and slope efficiencies of 53%, 62% and 54% were demonstrated for Cr:LiSAF, Cr:LiSGaF and Cr:LiCAF, respectively. Record cw tuning ranges from 782 to 1042 nm for Cr:LiSAF, 777 to 977 nm for Cr:LiSGaF, and 754 to 871 nm for Cr:LiCAF were demonstrated. In cw mode-locking experiments using semiconductor saturable absorber mirrors at 800 and 850 nm, Cr:Colquiriite lasers produced approximately 50-100 fs pulses with approximately 1-2.5 nJ pulse energies at approximately 100 MHz repetition rate. Electrical-to-optical conversion efficiencies of 8% in mode-locked operation and 12% in cw operation were achieved.

Fibre-coupled red diode-pumped Alexandrite TEM00laser with single and double-pass end-pumping

“…The form of Eq. (2) shows that the laser slope efficiency should be increasing with output coupling to an asymptotic limit: η s = η i . Fig.…”

Femtosecond tuning of Cr:colquiriite lasers with AlGaAs-based saturable Bragg reflectors

“…Cr 3þ :colquiriite (Cr 3þ :LiSAF [2], Cr 3þ :LiSGaF [3], and Cr 3þ : LiCAF [4]) lasers are a promising low-cost alternative to Ti:sapphire due to (i) their broad emission bands covering the 750-1050 nm spectral region and (ii) the possibility of direct diode pumping with low-cost laser diodes emitting around 650 nm [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Besides enabling a significant reduction in cost, direct pumping with high-brightness diodes also greatly improves electrical-to-optical conversion efficiency.…”

“…Besides enabling a significant reduction in cost, direct pumping with high-brightness diodes also greatly improves electrical-to-optical conversion efficiency. Among the Cr:colquiriites, Cr:LiSAF has the broadest gain and its demonstrated continuous-wave (cw) tuning range extends from 775 to 1042 nm [18] (extending to 1065 nm in pulsed operation [21]). Cr:LiCAF has received attention due to its blueshifted emission spectrum, which enables a cw tuning range of 754-871 nm [18] (extending to 720 nm in quasi-cw operation [4]).…”

“…Among the Cr:colquiriites, Cr:LiSAF has the broadest gain and its demonstrated continuous-wave (cw) tuning range extends from 775 to 1042 nm [18] (extending to 1065 nm in pulsed operation [21]). Cr:LiCAF has received attention due to its blueshifted emission spectrum, which enables a cw tuning range of 754-871 nm [18] (extending to 720 nm in quasi-cw operation [4]). To date, most femtosecond laser development efforts with Cr:colquiriites have focused on fixed wavelength operation near the gain peak, which is around 800 nm for Cr:LiCAF and 850 nm for Cr:LiSAF and Cr:LiSGaF.…”

“…Since the Kerr-lensing mechanism does not impose a bandwidth limitation, the shortest pulses and the broadest tuning range from Cr:colquiriite lasers have been obtained from KLM systems. However, the main difficulty with KLM mode-locked Cr:colquiriite lasers is the long-term stability and robustness of the mode-locked laser system, due to the relatively low nonlinear refractive index (n 2 ) of Cr:LiSGaF (1:2 × 10 −16 cm 2 =W), Cr:LiSAF (0:8 × 10 −16 cm 2 =W), and Cr:LiCAF (0:4 × 10 −16 cm 2 =W, which is 8 times smaller than Ti:sapphire [18,27]). Moreover, the efficiency (average output power/pump power) of the KLM Cr:LiSAF lasers is also relatively low due to the need for critical alignment of the cavity near its stability edge.…”